Since I made my last post about being unhappy with this dct I've learned more about its quirks and how to use it better. You're right, it does take time to get into 4th if shifted too quickly in a row. Not an issue on other dct cars I've driven though (m3, s4, gti, etc). But there is a workaround. If you go from 2nd to 3rd, and then do a later shift into 4th letting it Rev up around 5k or more, it goes into 4th instantly. Otherwise it just ignores you and shifts when it's good and ready, so it seems like it's a flaw at first, but I think it's like a way for the engine to prevent being short shifted at higher throttle inputs and bogging it down. In auto mode just cruising it is an amazing gearbox. With a louder exhaust you really hear the up and down shifts and it's super fun. Once you replace the factory muffler all the burbles and pops get louder. Also, it's crazy how heavy the stock muffler is!
I agree on letting off of gas when downshifting just like in a manual car. That applies to any type of driving, even mellow just cruising. It downshifts seamlessly with no throttle. Otherwise it just gets confused and becomes jerky and takes way longer to fully lock into gears. I notice in auto mode it has a solid 2-3 second delay for it to downshift on the freeway and start going under full throttle. Otherwise, like you said, in manual mode it downshifts and moves super quick, from 7th to 4th in less than a second. In auto it just can't drop down to those low gears fast with throttle applied, same logic as letting off gas in manual mode. So your method is exactly how I have been driving it.
On a side note, another thing I've discovered recently is that leaving the diverter hose unplugged on dct cars is a not a good idea. This applies to any aftermarket intakes that do not have a way to reattach the hose. After going back to stock intake I kept the hose open for the bov sound. I noticed some subtle lag in between shifts. It took longer to build boost again and felt like the car was falling on its face a bit. Once I reattached the hose the issue went away.